(a) Field of the Invention
The present invention relates to a plasma display panel (PDP), and in particular, to a barrier rib for a plasma display panel.
(b) Description of Related Art
Recently, the PDP has been spotlighted as a candidate for a wide screen display devices, such as a wall-mounted TVs and others. The PDP performs its displaying operation with a discharge mechanism realized at discharge cells. The discharge cells are formed by barrier ribs placed on the substrates in a suitable pattern (stripe or lattice).
As is well known in the art, the PDP is supported by a chassis base mounting a plurality of driving circuit boards at its rear side, and a front cabinet and a back cover are arranged at the front and the back of the PDP and chassis base, respectively. The front cabinet and the back cover are combined with each other in a body while interposing the PDP and the chassis base, thereby forming the outer structure of the display device.
The PDP-oriented display device has the advantages of a thin-thickness, and a light weight. However, when the display device undergoes impact or vibration of external loading, the PDP is liable to be bent or twisted, and this exhibits a structural weakness thereof.
With the PDP display device, the chassis base endures most of the loads and the distortions pursuant thereto, but is limited in its structural intensity. When an excessive external load is applied to the display device, the chassis base does not disperse it in a suitable manner. The excessive external load reaches the PDP, and particularly the barrier ribs mounted within the PDP, so that the substrates or the barrier ribs are broken or ruptured. In this case, the broken fractions of the substrates or the barrier ribs float in the PDP, and are introduced into the discharge cells, thereby interrupting or stopping the discharge operation within the relevant discharge cells. The resulting abnormal discharge can break the dielectric, causing device failure.
The PDP barrier ribs include main barrier ribs placed on the substrates within the display area where the display images are substantially made and dummy barrier ribs placed at the non-display area surrounding the display area. FIG. 16 is a schematic view of main and dummy barrier ribs in a PDP according to the prior art. FIG. 17 is a cross-sectional view of the PDP taken along the A—A line of FIG. 16. As can be seen, the main barrier ribs are formed with a stripe pattern. Dummy barrier ribs 3 contact the end portions 1a of main barrier ribs 1, and proceed perpendicular to main barrier ribs 1 (in the X direction of the drawing), thereby interconnecting the end portions 1a of main barrier ribs 1.
Barrier ribs 5 having main barrier ribs 1 and dummy barrier ribs 3 are formed using the technique of screen printing, sand blasting, squeezing, or photo processing. With techniques where firing is needed, the barrier rib paste is patterned and fired at 450° C. or more. With the firing process, the impurities and the binder residue in the barrier rib paste are fired, and the barrier rib paste is hardened to form a hard barrier rib.
When the barrier rib paste is fired, the paste-based film is contracted from its initial patterned state. The contraction proceeds along the direction of the length of the barrier rib to be formed later (in the Y direction of FIG. 16).
The paste portion corresponding to the end portion 1a of main barrier rib 1 is contracted toward the inside of the display area upon receipt of the contraction force (in the arrow direction of the drawing) directed thereto, and the paste portion corresponding to dummy barrier rib 3 is contracted while resisting the distortion of the paste portion corresponding to main barrier rib 1.
Assume in relation to the drawings that the horizontal portion of the dummy barrier rib 3 is indicated by a, the vertical portion of dummy barrier rib 3 connected to the end portion 1a of main barrier rib 1 by b, and end portion 1a of main barrier rib 1 placed within display area by c. The paste portion corresponding to vertical portion b of dummy barrier rib 3 is contracted and caved to a predetermined depth, due to the contraction force of the paste portion corresponding to main barrier rib 1 and the resistance force of the paste portion corresponding to dummy barrier rib 3. As shown in FIG. 17, the caved vertical portion of dummy barrier rib 3 is indicated by reference numeral 7. Furthermore, with the firing process, the paste portion corresponding to main barrier rib 1 and dummy barrier rib 3 is contracted, and as shown in FIG. 18, the corner portion of dummy barrier rib 3 is liable to be bent toward main barrier rib 1.
Accordingly, with the PDP having the above-structured barrier ribs 5, the bridge portion between main barrier rib 1 and dummy barrier rib 3 is unstably formed so that as shown in FIG. 19, gap 11 is made between the top surface of barrier rib 5 and front substrate 9. Consequently, a vibration is induced between front substrate 9 and rear substrate 13 while incurring noises, and this impairs the product quality and the structural stability of the PDP.